/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

#pragma once

#include <array>
#include <functional>
#include <string>
#include <string_view>
#include <utility>
#include <vector>
#include <igl/Common.h>

namespace igl {
// Constexpr as constexpr. In most cases all hashes from string would be generated in compile-time
// crc32 generation is based on gcc implementation

#define CRC_TABLE                                                                         \
  std::array<uint32_t, 256> kCrcTable = {                                                 \
      0,          0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, \
      0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, \
      0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, \
      0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, \
      0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, \
      0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C, \
      0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 0x26D930AC, \
      0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F, \
      0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, \
      0xB6662D3D, 0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, \
      0x9FBFE4A5, 0xE8B8D433, 0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, \
      0x086D3D2D, 0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, \
      0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, \
      0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, 0x4DB26158, 0x3AB551CE, \
      0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, \
      0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, \
      0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, \
      0xCE61E49F, 0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, \
      0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, \
      0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, \
      0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, 0xF00F9344, 0x8708A3D2, 0x1E01F268, \
      0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, \
      0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, \
      0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, \
      0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, \
      0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, \
      0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, \
      0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D, 0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, \
      0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, \
      0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242, \
      0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777, 0x88085AE6, \
      0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, \
      0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, \
      0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, \
      0x47B2CF7F, 0x30B5FFE9, 0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, \
      0xCDD70693, 0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, \
      0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D}

#if defined(__cpp_constexpr)
constexpr CRC_TABLE;

/**
 * @brief Calculates CRC32 for the incoming character array.
 * @param data null terminated character string
 * @returns CRC32 representation of data
 */
constexpr uint32_t iglCrc32ConstExpr(const char* p) {
  uint32_t crc = ~0u;
  for (; *p; ++p) {
    uint8_t v = (uint8_t)*p;
    crc = (crc >> 8) ^ kCrcTable[(crc & 0xFF) ^ v];
  }
  return ~crc;
}

constexpr uint32_t iglCrc32ConstExpr(std::string_view sv) {
  uint32_t crc = ~0u;
  for (auto p : sv) {
    uint8_t v = (uint8_t)p;
    crc = (crc >> 8) ^ kCrcTable[(crc & 0xFF) ^ v];
  }
  return ~crc;
}
#endif

/**
 * @brief Calculates CRC32 for the incoming character array.
 * @param data null terminated character string
 * @returns CRC32 representation of data
 */
uint32_t iglCrc32(const char* data, size_t length);

///--------------------------------------
/// MARK: - NameHandle

#if IGL_DEBUG_ABORT_ENABLED
#define CHECK_VALID_CRC(a) (void)checkIsValidCrcCompare(a)
#else
#define CHECK_VALID_CRC(a)
#endif

/**
 * @brief Creates a mapping between a string and its equivalent CRC32 handle
 * This way when we need to check if a uniform exists or if it matches another
 * uniform, we can do an integer comparison rather than a string comparison.
 */
class NameHandle {
 public:
  NameHandle() = default;
  ~NameHandle() = default;

  NameHandle(const NameHandle& other) = default;
  NameHandle(NameHandle&& other) noexcept = default;

  NameHandle(std::string name, uint32_t crc32) : crc32_(crc32), name_(std::move(name)) {}
  NameHandle(const char* name, uint32_t crc32) : crc32_(crc32), name_(name) {}
  NameHandle(std::string_view name, uint32_t crc32) : crc32_(crc32), name_(name) {}

  /**
   * @brief Returns a null terminated character array version of the name
   * @returns null terminated character array
   */
  [[nodiscard]] const char* c_str() const {
    return name_.c_str();
  }

  /**
   * @brief Returns a reference to the actual name string
   * @returns Reference to the actual name string
   */
  [[nodiscard]] const std::string& toString() const {
    return name_;
  }

  /**
   * @brief Returns crc32 handle for the name string
   * @returns crc32 handle
   */
  [[nodiscard]] uint32_t getCrc32() const {
    return crc32_;
  }

  bool operator==(const NameHandle& other) const {
    CHECK_VALID_CRC(other);
    return crc32_ == other.crc32_;
  }

  bool operator!=(const NameHandle& other) const {
    return !(*this == other);
  }

  bool operator<(const NameHandle& other) const {
    CHECK_VALID_CRC(other);
    return (crc32_ < other.crc32_);
  }

  bool operator>=(const NameHandle& other) const {
    return !(*this < other);
  }

  bool operator>(const NameHandle& other) const {
    CHECK_VALID_CRC(other);
    return (crc32_ > other.crc32_);
  }

  bool operator<=(const NameHandle& other) const {
    return !(*this > other);
  }

  NameHandle& operator=(const NameHandle& other) {
    if (crc32_ == other.crc32_) {
      return *this;
    }

    crc32_ = other.crc32_;
    name_ = other.name_;
    return *this;
  }

  NameHandle& operator=(NameHandle&& other) noexcept = default;

  operator const char*() const {
    return name_.c_str();
  }

 private:
#if IGL_DEBUG_ABORT_ENABLED
  [[nodiscard]] bool checkIsValidCrcCompare(const NameHandle& nh) const;
#endif
  uint32_t crc32_ = 0;
  std::string name_;
};

/**
 * @brief Helper function to convert a string to a NameHandle
 * @param name String to convert
 * @return NameHandle that includes the name and its CRC32.
 */
inline NameHandle genNameHandle(const std::string& name) {
  return {name, iglCrc32(name.c_str(), name.length())};
}
} // namespace igl

#if defined(__cpp_constexpr)
/// @def IGL_DEFINE_NAMEHANDLE_CONST(name, str)
/// @brief Declares and assigns a named igl::NameHandle variable.
/// @param name The name of the NameHandle variable.
/// @param str The name the handle represents (e.g., uniform name). Must be a const char*.
#define IGL_DEFINE_NAMEHANDLE_CONST(name, str) \
  const igl::NameHandle name(str,              \
                             std::integral_constant<uint32_t, igl::iglCrc32ConstExpr(str)>::value)

/// @def IGL_NAMEHANDLE(str)
/// @brief Creates an igl::NameHandle instance.
/// @param str The name the handle represents (e.g., uniform name). Must be a const char*.
#define IGL_NAMEHANDLE(str) \
  igl::NameHandle(str, std::integral_constant<uint32_t, igl::iglCrc32ConstExpr(str)>::value)

#else
// To avoid stlib include, this function is trivial
inline size_t iglStringlength(const char* str) {
  size_t r = 0;
  while (*str++) {
    r++;
  }
  return r;
}
#define IGL_DEFINE_NAMEHANDLE_CONST(name, str) \
  const igl::NameHandle name(str, igl::iglCrc32(str, iglStringlength(str)))
#define IGL_NAMEHANDLE(str) igl::NameHandle(str, igl::iglCrc32(str, iglStringlength(str)))
#endif

/// @def IGL_NAMEHANDLE_ACCESSOR(name)
/// @brief Declares a function returning a const igl::NameHandle& instance.
/// @param name The name of the NameHandle function to create.
///
/// Use IGL_NAMEHANDLE_ACCESSOR_IMPL to define the function body.
/// Use these to avoid compiler warnings with file-scoped const NameHandle instances.
/// TODO: Remove once C++20 can be used as NameHandle can be constexpr.
#define IGL_NAMEHANDLE_ACCESSOR(name) const ::igl::NameHandle& name();

/// @def IGL_NAMEHANDLE_ACCESSOR_IMPL(name, str)
/// @brief Defines a function returning a const ref to a local static igl::NameHandle instance.
/// @param name The name of the NameHandle method to create.
/// @param str The name the handle represents (e.g., uniform name). Must be a const char*.
///
/// Use IGL_NAMEHANDLE_ACCESSOR to declare the function prototype.
/// Use these to avoid compiler warnings with file-scoped const NameHandle instances.
/// TODO: Remove once C++20 can be used as NameHandle can be constexpr.
#define IGL_NAMEHANDLE_ACCESSOR_IMPL(name, str)    \
  const ::igl::NameHandle& name() {                \
    static IGL_DEFINE_NAMEHANDLE_CONST(name, str); \
    return name;                                   \
  }

namespace std {

template<>
struct hash<igl::NameHandle> {
  size_t operator()(const igl::NameHandle& key) const {
    return hash<uint32_t>()(key.getCrc32());
  }
};

template<>
struct hash<pair<igl::NameHandle, igl::NameHandle>> {
  size_t operator()(const std::pair<igl::NameHandle, igl::NameHandle>& key) const {
    return hash<uint32_t>()(key.first.getCrc32()) ^ hash<uint32_t>()(key.second.getCrc32());
  }
};

template<>
struct hash<vector<igl::NameHandle>> {
  size_t operator()(const std::vector<igl::NameHandle>& key) const;
};

} // namespace std
